Show 97. Notes for April 30th
Shows are recorded live on the Darkmatterradio.net every Wednesday at 8:00 PM Eastern Standard Time, GMT/00:00 UTC and podcasts of the live shows posted the following Thursday. You can join the Chat Room on right sidebar of our home page and interact live each week.
SpaceX Dragon is currently docked with the International Space Station. Check out the awesome interactive website: http://www.spacex.com/dragon
As our regulars know, I steal the news from our facebook page, and Peggy Shunning admins that and digs up some great stuff. Canadian witnesses see UFO at 400 ft .. if you look at the picture, you may agree with our past guest, Ben Hurle who chimed in saying it is probably a drone. I think jhe is right, jump on over to podcast ufo in the show notes and see for yourself.
Exoplanets in Multiple Star Systems
by Andy Fleming
Science fiction has long depicted the idea of alien life on planets in multiple star systems, such as Star Wars’ Tatooine. And yet, until recently mainstream science speculated that planets in such systems were impossible. If they formed at all, they would be ejected due to complex gravitational interactions.
Our Sun is a single star, but astronomers have known for decades that most stars in our galaxy are in multiple star systems containing one, two or even more stars. Amazingly, it turns out through astronomical observations that planets are present in these complex systems too.
For starters, there are circumbinary planetary systems of which seventeen have been discovered. The stars here are in close orbit with the planets orbiting outside. These are the gravitational equivalent of a single star.
More difficult for planetary formation are wide binary systems, where planets orbit one main star, the other star maintaining an orbit much further out. The gravitational interactions are chaotic. In simulations, planets which aren’t tightly orbiting a star are ejected from the system. Such a scenario may well be present in the constellation of Cygnus with star HD 188753. A pair of stars are in a wide but tightly bound binary arrangement with a sun-mass star. A planet closely orbits the primary star, but all other planets were likely ejected.
A further major discovery occurred in 2012 when a planet was found around Alpha Centauri B, part of the triple star system next door.
Next, PH1 was the first quadruple star system to be discovered to have a planet.
Finally, Kepler 47 turns out to be a multi-star, multi-planet system. Two stars orbit one another every seven days. Here, the gas giant Kepler 47c orbits the stars every three hundred days and is even located in the habitable zone.
But how about this. In 2011 the Kepler-16 system was found to have a Saturn-mass circumbinary planet in the habitable zone that astronomers called a real Tatooine.
Such discoveries raise the exciting prospect that additional planets may exist in the Alpha Centauri system. They could orbit Alpha Centauri A or Alpha Centauri B individually, or be on large orbits around the binary Alpha Centauri AB. Since both the principal stars are fairly similar to the Sun, astronomers have been using various radial velocity or star transit methods to look for planets in a star system just 4.3 light years away.